1. Field of the Invention
The present invention relates to a decoding circuit widely used for example, in a data communication apparatus. More particularly, the invention relates to a method for decoding original data at the receiving side which is encoded differently from the original data for error correction. In addition to the decoding method, a circuit for carrying out the method is provided.
2. Description of the Prior Art
FIG. 1 is a typical block diagram of a general communication system for data communication.
In FIG. 1, reference numeral 55 designates a signal line connected to an encoder 51 for transmitting data.
When one-bit data to be transmitted is input from the signal line 55, is in the form of a logical "1", and encoder 51 encodes the data to 3-bit data of logical "111." When the same is a logical "0", 3-bit data of logical "000" is encoded and output to a transmitter 52.
The transmitter 52 outputs to a channel 56 the signal by 3-bit unit received from the encoder 51.
Reference numeral 53 designates a receiver, which receives the signal transmitted through the channel 56 and inputs it to a decoder 54.
When 2-bits of the 3-bits of the data from the receiver 53 is a logical "1", the decoder 54 outputs 1-bit data of logical "0" to a signal line 7. When 2-bits are logical "1", 1-bit data of logical "0" is output to the same.
Such constitution is described in "Key Point of Error Correction Encoding Technique" (Mar. 20, 1986) published by Japanese Industrial Technology Center, which is effective to correct an error generated in the channel 56.
The above method converts the 1-bit data into 3-bits and transmits it. At the receiver side the 3-bit data is compared and decoded into 1-bit data and output. A problem is created in that it takes a relatively long processing time to decode the data.